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Convection plans

Convection plans. Alison Stirling. Priorities for convection parametrization. Main Systematic Errors: Diurnal cycle MJO Monsoons AEW coupling. Transient response to boundary layer. Feedback with `large-scale’ environment. Interaction with large scale. Ascent generates CAPE.

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Convection plans

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  1. Convection plans Alison Stirling

  2. Priorities for convection parametrization Main Systematic Errors: Diurnal cycle MJO Monsoons AEW coupling Transient response to boundary layer Feedback with `large-scale’ environment

  3. Interaction with large scale Ascent generates CAPE Heating generates ascent Depth and amplitude of convective response key to improving monsoon, MJO, AEW coupling

  4. Interaction with large scale progress and further work: Increased entrainment improves coupling between convection and large-scale (Klingaman et al 2013) …but it can’t be high all the time… Introduce physically realistic entrainment dependence: (stability and cloud area) Explore effects of large scale on other parts of scheme UM high resolution convection simulations over a large domain allows circulations resulting from convection to develop.

  5. Interaction with boundary layer Introduce energetics of boundary layer thermals Modify triggering and closure to have dependence on this Cold pools Important for: 1. Triggering and closure Additional KE to overcome CIN Temperature and moisture differences allow CAPE to be present locally even when the mean state is stable Enhanced lifting 2. Entrainment affects cloud area (and therefore buoyancy and vertical velocity) Two zones of temperature and moisture Requires memory of previous precipitation events MOAP secondment to work on cold pools

  6. Research areas

  7. Convection position available! See www.metoffice.gov.uk/about-us/jobs/ Closing date: 14th July 2013 Higher resolutions • Mass flux: Separate into component parts • vertical velocity, cloud area, and cloud number • Multiple plume: Quantify the need for a multi-plume approach Allows: • grid-size sensitivity, • inclusion of microphysics • better coupling with PC2 • stochasticity Applications submitted for Reading and Leeds CASE students to work on different aspects of grey-zone problem.

  8. Questions and answers

  9. Unification Give each component of the existing convection scheme an improved physical basis. • Entrainment: Include dependence on stability and cloud area • Detrainment: Reformulate to be adaptive all the way up the cloud, and let the level of adaptivity depend on cloud area • Triggering and closure: Base on energetics of boundary layer processes and large-scale ascent

  10. Unification details • Research areas include: • Cloud area representation • Cold pool representation • Boundary layer thermal energetics • Convective response to large-scale ascent

  11. UM runStu Webster • Indian Ocean • 200m from 2.2km b.c.s • 4000 x 2600 points • 3 days • http://www-hc/~hadsw/dkrf/gifs/dkrfw.10000.full.gif

  12. What controls convective depth? • Vertical extent of CAPE • Entrainment • Detrainment Cloud area? Boundary layer processes? (e.g. cold pools) High entrainment increases coupling to LS ascent/ descent, but it can’t be high all the time!

  13. What controls heating amplitude? Rate of CAPE creation? • Closure Inversion removal? Ascent?

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